4.9-stable review patch. If anyone has any objections, please let me know.
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From: Will Deacon will.deacon@arm.com
commit 6c27c4082f4f upstream.
The literal pool entry for identifying the vectors base is the only piece of information in the trampoline page that identifies the true location of the kernel.
This patch moves it into a page-aligned region of the .rodata section and maps this adjacent to the trampoline text via an additional fixmap entry, which protects against any accidental leakage of the trampoline contents.
Suggested-by: Ard Biesheuvel ard.biesheuvel@linaro.org Tested-by: Laura Abbott labbott@redhat.com Tested-by: Shanker Donthineni shankerd@codeaurora.org Signed-off-by: Will Deacon will.deacon@arm.com [Alex: avoid ARM64_WORKAROUND_QCOM_FALKOR_E1003 dependency] Signed-off-by: Alex Shi alex.shi@linaro.org [v4.9 backport] Signed-off-by: Mark Rutland mark.rutland@arm.com [v4.9 backport] Tested-by: Will Deacon will.deacon@arm.com Tested-by: Greg Hackmann ghackmann@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm64/include/asm/fixmap.h | 1 + arch/arm64/kernel/entry.S | 14 ++++++++++++++ arch/arm64/kernel/vmlinux.lds.S | 5 ++++- arch/arm64/mm/mmu.c | 10 +++++++++- 4 files changed, 28 insertions(+), 2 deletions(-)
--- a/arch/arm64/include/asm/fixmap.h +++ b/arch/arm64/include/asm/fixmap.h @@ -53,6 +53,7 @@ enum fixed_addresses { FIX_TEXT_POKE0,
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 + FIX_ENTRY_TRAMP_DATA, FIX_ENTRY_TRAMP_TEXT, #define TRAMP_VALIAS (__fix_to_virt(FIX_ENTRY_TRAMP_TEXT)) #endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -881,7 +881,13 @@ __ni_sys_trace: msr tpidrro_el0, x30 // Restored in kernel_ventry .endif tramp_map_kernel x30 +#ifdef CONFIG_RANDOMIZE_BASE + adr x30, tramp_vectors + PAGE_SIZE + isb + ldr x30, [x30] +#else ldr x30, =vectors +#endif prfm plil1strm, [x30, #(1b - tramp_vectors)] msr vbar_el1, x30 add x30, x30, #(1b - tramp_vectors) @@ -924,6 +930,14 @@ END(tramp_exit_compat)
.ltorg .popsection // .entry.tramp.text +#ifdef CONFIG_RANDOMIZE_BASE + .pushsection ".rodata", "a" + .align PAGE_SHIFT + .globl __entry_tramp_data_start +__entry_tramp_data_start: + .quad vectors + .popsection // .rodata +#endif /* CONFIG_RANDOMIZE_BASE */ #endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */
/* --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -252,7 +252,10 @@ ASSERT(__idmap_text_end - (__idmap_text_ ASSERT(__hibernate_exit_text_end - (__hibernate_exit_text_start & ~(SZ_4K - 1)) <= SZ_4K, "Hibernate exit text too big or misaligned") #endif - +#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 +ASSERT((__entry_tramp_text_end - __entry_tramp_text_start) == PAGE_SIZE, + "Entry trampoline text too big") +#endif /* * If padding is applied before .head.text, virt<->phys conversions will fail. */ --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -435,8 +435,16 @@ static int __init map_entry_trampoline(v __create_pgd_mapping(tramp_pg_dir, pa_start, TRAMP_VALIAS, PAGE_SIZE, prot, pgd_pgtable_alloc, 0);
- /* ...as well as the kernel page table */ + /* Map both the text and data into the kernel page table */ __set_fixmap(FIX_ENTRY_TRAMP_TEXT, pa_start, prot); + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { + extern char __entry_tramp_data_start[]; + + __set_fixmap(FIX_ENTRY_TRAMP_DATA, + __pa_symbol(__entry_tramp_data_start), + PAGE_KERNEL_RO); + } + return 0; } core_initcall(map_entry_trampoline);